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Methods to characterise the performance of CCD cameras for electron detection are investigated with particular emphasis on the difference between the transfer of signal and noise. Similar to the Modulation Transfer Function MTF, which describes the spatial frequency dependent attenuation of contrast in the image, we introduce a Noise Transfer Function NTF that describes the transfer of the Poisson noise that is inevitably present in any electron image. A general model for signal and noise transfer by an image converter is provided. This allows the calculation of MTF and NTF from Monte‐Carlo simulations of the trajectories of electrons and photons in the scintillator and the optical coupling of the camera. Furthermore, accurate methods to measure the modulation and noise transfer functions experimentally are presented. The spatial‐frequency dependent Detection Quantum Efficiency DQE, an important figure of …